Re: [CAD_CAM_EDM_DRO] A crazy idea

Hi Mariss,

I think I'd rather use EPP or ECP techniques for the parallel port
interface, that is , just MULTIPLEX the bits out somehow. That way, we
could keep compatible with existing step/dir hardware and software. OR,
an additional parallel port gives more pins! But thanks for the ideas!

Alan KM6VV


mariss92705 wrote:

>
> Hi,
>
> Parallel port output CNC programs are limited to 3 or 4 axies because
> of the limited number of port bits. Each axis requires a STEP and
> DIRECTION bit pair. What if it could be done with a single bit per
> axis where STEP and DIRECTION were combined on the same line? It then
> would be possible to run 6 to 8 axies.
>
> Here's how it could be done:
>
> (1) 100000000010000000001000... is CW
> (2) 011111111101111111110111... is CCW
>
> In (1), a narrow positive going pulse would be interpreted as a CW
> motion. In (2), a narrow negative going pulse would result in CCW
> motion at the same speed. One would simply invert (1) to generate (2).
>
> This scheme would place no additional burden on the software or on
> the bandwidth of the now combined STEP/DIRECTION compared to a
> standard STEP pulse line. Decoding hardware in the drive would be
> minimal; just a single quad gate package.
>
> So, what do you think, a crazy idea?
>
> Mariss
>
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